1. Field of the Invention
The present invention relates generally to flush valves and, in particular, to a rigid piston for use in a flush valve.
2. Description of Related Art
Valves are used throughout many fluid transfer systems and in various applications, such as in the transfer and control of water conduit systems, and, in particular, in connection with plumbing fixtures in both residential and commercial settings. For example, flush valves are typically used for control and operation of toilets, urinals, and the like, such that when a user actuates a handle, water flows through the flush valve into a basin portion and out the drain.
A common type of flush valve is a diaphragm flush valve. Such a diaphragm flush valve is disclosed in U.S. Pat. No. 4,327,891 to Allen et al., herein incorporated by reference. The Allen patent discloses the use of a diaphragm in a flush valve, where the diaphragm is made of molded rubber and serves to effectuate the flow of water from a water inlet, through the valve, and to a water outlet. Further, the Allen patent sets forth various components and sub-components of a conventional flush valve.
Such diaphragm flush valves have several drawbacks. For example, the relatively small by-pass orifice positioned in the diaphragm can become clogged with debris, which prevents water from flowing into an upper chamber located in the flush valve. This causes the flush valve to remain open, resulting in constant water flow. In addition, the flushing cycle of the diaphragm flush valve takes approximately seven seconds to complete, depending upon the flow rates and pressure of the water entering the valve, due to the design of the diaphragm of the flush valve. Since an upper chamber fills slowly, the valve is slowly “shutting off”. Therefore, a significant amount of water is wasted through the trap and sewer line during the sealing process of the valve. Yet another drawback is that conventional diaphragm flush valves are impacted at water pressures below 35 psi, since sealing of the valve based on the water pressure against the diaphragm is difficult with such lower water pressure. A need, therefore, exists for a valve replacement element that can effectively be retrofitted into a flush valve that does not have the drawbacks associate with conventional diaphragm flush valves. A further need exists for a flush valve having improved sealing features.